During his trial, the court heard he had taken cocaine between eight and 20 hours before the crash which may have dulled his concentration and reactions.

Following the verdict, Bett wiped his eyes and his girlfriend wept as Judge Peter Murphy warned him: “A custodial sentence is extremely likely.”

Mrs Brown’s bereaved husband also wept from the public gallery.

Prosecutor Simon Wilshire said Bett already had three speeding endorsements.

He was given an immediate, interim disqualification from driving and freed on bail pending his sentencing on August 20.

The judge heard he is also being investigated for alleged speeding and careless driving in a Land Rover last month.

Adrian Foster, Chief Crown Prosecutor for the Thames and Chiltern Crown Prosecution Service, said: “It is likely that his use of cocaine 12 to 24 hours before the collision caused a lack of concentration and the slowing of his reactions.

“It should act as a reminder to others that any use of drink/drugs before driving or operating machinery can have very serious consequences.

“This was a very sad case, the consequences of which have had a terrible impact on many lives. The victim was a wife and mother, and her family and friends have been devastated by her death.”